1. Field of the Invention
This invention relates to a hand operated device for bending metal bars and the method of use thereof. The device is particularly adapted, although not restricted, to bending bars used to reinforce concrete, generally known as rebars. Rebars are typically made of steel or iron and after they are bent they are placed inside concrete before the concrete is poured. The device of the present invention is portable and hand operated, therefore, it may be transported readily to a construction site and used in-field without need for an external source of power.
2. Description of the Prior Art
In the past, bending of rebars was usually done away from the construction site and the pre-bent rebars were transported ready for use to the site. Under such circumstances it was necessary to predetermine the number of rebars needed at the construction site. It was also necessary to predetermine the angle to which the bars should be bent, the number of bends which should be made in each rebar and the relative locations of the bends. Usually it was not feasible or possible to bend bars on the site to accommodate needs as they arose although some such prior art devices existed. However, they required that the metal bar be threaded through holes in the devices, or into passages or the like which resolved the devices time consuming and cumbersome to use.
U.S. Pat. No. 1,054,132 to Miner discloses a portable bending machine for bending corner bars of steel. Such bars were used to protect concrete covered street curbs. The device disclosed by Miner has two stationary blocks which support an initially straight bar. A lever is depressed and a ram pushes the bar towards the stationary blocks, thereby causing the bar to curve. The bending device disclosed in the Miner patent, though portable, is not well suited for use in the environment of a construction site; its construction is too heavy therefor, it requires flat support surfaces which are typically not available at a construction site, and it is cumbersome to use, especially when making reverse bends.
Other prior art patents disclose stationary bending machines for use in a manufacturing plant. Examples of such prior art are U.S. Pat. No. 3,333,445 to Mergler, which discloses a bending system which is digitally controlled, and British Pat. No. 1,243,199 to Clement et al., which discloses a device used to bend a metal sheet.